Light-emitting diode light strings are widely used by users on building exteriors, trees, signboards, and landscapes to add aesthetic appeal. At present, it can be roughly divided into two types of connection methods: series connection and parallel connection. The series light-emitting diode light string connects a plurality of light-emitting diodes in series. Although the series connection method makes the light-emitting diode light string module easy to be produced, failure of one light-emitting diodes will not enable the electric current to be transmitted during use, so that the entire diode light string cannot be lit. Parallel light-emitting diode light strings are a combination of multiple light-emitting diodes connected in parallel. Each light-emitting diode light string has several light-emitting diodes. In order to achieve the synchronization, asynchronous or point control effect of the light-emitting diode light strings, each light-emitting diode connected to the light-emitting diode light string will be made to have one address coding, and each light-emitting diode must have a control line and an address line to control it. If 10 light-emitting diodes are connected in parallel, 10 control lines and 10 address lines must be used to control the 10 light-emitting diodes. The greater the number of light-emitting diodes connected in parallel, the more the control lines and address lines, resulting in complicated circuits, difficult to manufacture, and high cost.
Chinese patent for invention 201510402773.7 discloses a light-emitting diode light string control system. The light-emitting diode driving device includes a switching unit, a control unit and a voltage level generating unit. The switching unit is electrically connected to the light-emitting diode light string and the control unit. The voltage level generating unit is electrically connected to the output end of the light-emitting diode driving device and the light-emitting diode light string. The Zener diode ZD of the voltage level generating unit is connected in parallel with the capacitor C. The cathodes of the Zener diode ZD connected in series with the resistor R5 are connected to the rectified input end by the alternating current power supply and the anode of the series diode D, respectively, then electrically connected with the light-emitting diode light string. The anode of the Zener diode ZD is grounded, and the Zener diode ZD determines the output voltage value of the voltage level generating unit. When the output voltage of the voltage level generating unit is not high, such as 3 to 6 v, there are fewer zener diodes that meet the requirements, and zener diodes below 6V belong to zener breakdown, and the voltage stabilizing characteristics are not as good as avalanche breakdown. When a short-circuit fault occurs in a series light-emitting diode light string, the line current increases, and it is easy to burn out the light-emitting diode light string and the power supply, there is even a dangerous situation of fire, which will cause a potential safety hazard. Current light-emitting diode light string is usually provided with a short-circuit protection circuits at the output end, but the short-circuit protection circuits are more complicated and require more components. Although the potential safety hazard can be avoided, when the short-circuit fault of the light string is resolved, the light-emitting diode light string control system cannot resume normal operation by itself, it can only be abandoned, which cause waste of resources.